Castorus is a Chrome extension that allows users to track real estate listings and shopping prices in a community-driven manner. By installing the extension on your browser, Castorus automatically captures essential information from real estate ads and products that you view.

For real estate listings, Castorus provides valuable insights such as price changes, modifications, other links where the ad has been seen, what you can get for the same price, and even financing options for the property. For products, Castorus offers price trends and suggests alternative websites where you can find the same product at a lower price.

One of the key features of Castorus is its community-driven approach. Users anonymously share their real estate and shopping information, allowing you to access the historical data of an ad or product even if you are the first user to view it.

Please note that since 2017, Castorus only functions on professional real estate portals to ensure the protection of personal data. It does not support general classifieds websites for individual users with a real estate section, such as Le Bon Coin.